Weigert



March 3, 1964 K. WEIGERT 3,123,033

BACKTACKING ATTACHMENT Fild Oct. 16, 1961 INVENTOR KARL WEISERT M MW ATTORNEY United States Patent 3,123,033 EACKTACKING ATTACHMENT Karl Weigert, Rego Park, Queens, N.Y., assignor to Reliable Attachment Co., New York, N.Y. Filed Oct. 1%, 1961, Ser. No. 145,278 13 Claims. (Cl. 112-197) This invention relates to sewing machine attachments implementing the tacking down of any free chain of stitches, more particularly to a sewing machine attachment for use in connection with overedge or overlock stitch machines.

In most sewing machine operations it is desirable to tack .Of secure the threads at the ends of a line of stitches so as to effect a locking of the stitches. Where this tacking to effect locking is not performed, there is often a raveling of the stitched threads.

In the case of machines such as overedge or overlock machines like the Singer 246 Overlook or similar machinery manufactured by Willcox and Gibbs, Merrow, or Union Special a plurality of strands of thread are fed to the needle plate and form a chain stitch which in addition to extending through the material, extends over the edge of the material from top to bottom to provide an edge binding or overlock. This stitch is formed by utilizing a chain finger on the needle plate of the machine with the chain finger acting as a support for the fonnation of the stitch by the thread loopers and needle in much the same way that a finger is utilized to aid in tying a bow on a package. The formed stitch is thus an interlocking chain which though extending through the material does not require the material for its formation, and in sewing with equipment of this type there is generally a run out chain of stitches or a tail formed at the end of each course of stitching. In order to obtain a clean finish,

it is necessary to eliminate the aforedescribed free chains or tails. The tail of stitches should not be cut off since this may result in a raveling of the stitch. It is desirable to tack the end of the run of stitches, preferably by sewing the tail into the line of the stitching.

Equipment of this type is utilized in conjunction with stretch materials such as knit goods, tricots or the like. Additionally, multi-ply goods such as quilted materials are most effectively sewn along their edges by overlock machines.

Where the overedge or overlock machine is used, removal of the sewn material from the sewing area requires a continuation of stitch or chain formation. Thus, upon the commencement of sewing of any given course of stitches, a preormed free chain or tail exists which has been formed as a result of freeing of the previously sewn material from the sewing area. This chain must be eliminated in order to obtain a clean finish at the edge of a garment.

in normal use in the stitching of knit goods such as shirts, sweaters, under arments or the like, the clean finish is desired at the commencement of the line of stitching, either at the sleeve, neckband, or waistline of the garment.

In this normal situation, the operator runs the material through the stitching area leaving a chain or tail of free stitches which is cut by bringing the chain or tail around to the front of the machine against a cutting blade. This necessitates lifthig the presser foot to permit swinging the free tail of the chain. Thereafter the material to be sewn is inserted beneath the presser foot, the presser foot is lowered, the line of stitches is commenced, and when the previously formed tail is free the operator lifts the presser foot, swings the tail around to align same with the stitches being formed, lowers the presser, and continues sewing so as to engage the tail in the newly formed line of stitches. As appears from the above description, the

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presser foot must be lifted once for cutting, and a second time for backtacking. Additionally the operator must swing the free tail twice. Other problems arise in that alignment of the tail with the formed row of stitches is haphazard, in that the row of stitches being formed is not visible to the operator.

It is with the above problems in mind, that the present means have been evolved, means including both method and apparatus, implementing the backtacking of the free tail of a chain of stitches formed on an overlock machine. The novel means require a single raising of the presser foot, and a single movement of the free tail, with said movement serving to simultaneously align the free tail with the row of stitches to be formed, and cut off the tall from the previously formed row of stitches.

It is accordingly a primary object of this invention to provide a novel attachment for overedge or overlocking sewing machines implementing the backtacking of the free tail of the chain of stitches.

A further object of the invention is to provide a novel method implementing the backtacking of a free chain or tail of stitches on an overedge or overlock sewing machine.

A further object of the invention is to provide means implementing backtacking on an overlock sewing machine serving to simultaneously align the free chain or tail of stitches, and sever same from the previously formed chain of stitches.

It is also an object of the invention to provide novel means for discontinuing the formation of the chain of stitches on an overlock machine while the machine is energized. so as to permit material feed without chain formation.

It is a further object of the invention to provide novel means for cutting a tail of a chain in which said cutting means are not exposed to contact by the operator.

It is also an object of the invention to provide a novel chain finger for the throat plate of an overlock machine which permits selective discontinuance of thechaining operation at the will of the operator.

Another object of the invention is to provide improved means for retaining the tail of the chain in alignment with the row of stitches being formed to implement backtackmg.

These and other objects of the invention are accomplished by providing a novel throat or needle plate for an overedge or overlock machine. The novel needle plate is formed with an undercut adjacent the chain finger to permit withdrawal of the thread from the chain forming area to prevent the chain forming interaction between the thread loopers of the machine. Additionally a novel cutting knife is arranged in combination with the needle plate hidden by a knife guard so that the tail of the chain may be brought against the knife, but the knife is not subject to contact by the operator. A hold down spring clamp is arranged adjacent the knife and overlying the plate so that when the chain is moved to a cut off position it is simultaneously retained in line with the row of stitches to be formed and within the chain finger undercut so that by the single operation of swinging the tail of the chain to a severing position, the tail is simultaneously aligned for backtacking, severed, and the chaining operation is discontinued until the material reaches the sewing area.

An important feature of the invention resides in the chain finger undercut which permits movement of the thread to a position preventing chain formation pending the movement of the material to be sewn to the sewing area.

Another feature of the invention resides in the novel combination of the cutting knife, the knife guard, and

the spring clamp which permits thread severing but prevents operator contact with the knife.

The specific details of a preferred embodiment of the B invention, and their mode of functioning will be made most manifest and particularly pointed out in clear, concise and exact terms in conjunction with the accompanying drawings, wherein:

FIG. 1 is a top plan view of the novel needle plate embodying the features of the instant invention; and

FIG. 2 is an end view of the novel plate looking from the right of FIG. 1; and

FIG. 3 is an end view of the novel plate looking from the bottom of FIG. 1; and

FIG. 4 is an exploded view of the orienting and cutting assembly.

Referring now more particularly to the drawings, like numerals in the various figures will be taken to designate like parts.

The novel throat or needle plate It is formed with an attaching car 11 (as seen to the right in FIG. 1) having appropriate bolt holes 12 to permit attachment to the machine. Appropriate dog openings 14 are provided in the plate in conventional fashion to accommodate the material moving dogs of the machine, and appropriate anti-backsliding teeth 15 are formed adjacent the dog openings in conventional fashion.

The chain finger 18 is formed integrally with the plate and an undercut 20 is formed between the plate and the chain finger extending downwardly as viewed in FIG. 1 away from the stitch forming area which lies between the dash lines x and y respectively. A chain stop 22 is provided to the right of the chain finger 18 as viewed in FIG. 1.

At the front right of the needle plate 10 (to the lower right as viewed in FIG. 1) the chain tail orienting and cutting assembly 25 is arranged. Orienting and cutting assembly 25 comprises a mounting bracket 26 having a flange 27 through which machine screws 28 extend to permit securement of the mounting bracket to the main portion of plate 10. A thread cutting knife 34 formed preferably of an L-shaped piece of steel or the like as viewed in FIG. 4 is provided with an attaching flange 31 which lies between flange 27 and plate body 10.

Thread retaining spring clamp 35 is secured to mounting bracket 26 in a position adjacent knife blade 30. An entry lip 36 is formed on the free end of spring clamp 35 to implement insertion of the tail of the chain beneath the clamp. Adjusting screw 37 extends through spring clamp 35 into bracket 26 for a purpose to be made hereafter more apparent. Assembly screw 38 secures the spring clamp in position on bracket 26, along with knife guard 4%. Knife guard 49 has a flange 41 overlying the blade of knife 3i) as best seen in FIG. 3.

Operation The novel throat or needle plate 19, as above described is utilized to implement backtacking on an overedge or overlock stitch machine such as the previously mentioned Singer 246 or the like overlock stitch machines manufactured by Willcox and Gibbs, Merrow and the Union Special. In use, the conventional throat or needle plate of the aforementioned overlock machines is replaced by the instant novel needle plate 10. The operator proceeds to sew material conventionally sewn on such machines such as rayon, tricot, silk, muslin, light denim, flannel balbriggan knit goods, sweater materials, quilted materials, and the like loosely structured fabrics to provide an over-edge type needle stitch and simultaneously trim the edge beyond the stitch.

These machines as discussed cannot have the thread pulled through their needles and loopers, and in order to move the material away from the sewing area, it is necessary to energize the machine which in normal operation results in a continuation of stitch formation producing the chain stitch of the machine. Where the novel needle plate is utilized, after a given piece of material is sewn, the operator continues energizing the machine to permit re moval of the material from the sewing area, thereby coni tinuing stitch formation to produce a free tail of a chain of stitches.

The operator lifts the foot of the machine and swings the free chain or tail T around in the direction of the arrows as viewed in FIG. 1 so that the tail T rides beneath entry lip 36 to underlie spring clamp 35 and simultaneously move against the cutting knife 34? thereby severing the tail and releasing the previously sewn material.

The new material to be sewn is inserted beneath the foot in the direction of the solid line arrow pointing upwardly in FIG. 1 and indicating the direction of material movement, and the foot lowered. It will be observed that by movement of tail T to the position overlying clamp 35 the thread is pulled into undercut 20 away from the stitch forming area lying between lines x and y on FIG. 1 in which loopers L and L interact with the needle and chain finger 18 to form a chain of stitches. Under these circumstances no stitch formation takes place during machine energiz-ation. The material to be sewn is positioned over the feed dogs extending through feed dog openings 14- and 15, the press-er foot is lowered, and the machine is energized. No stitch formation takes place however until the movement of the material alongthe chain finger fonces the thread out of the undercut 29 into the sewing area between lines x and y. At this time chain formation commences and the material is simultaneously sewn and trimmed with the formed chain serving to backtack the tail which has previously been drawn back into position beneath spring clamp 35.

Adjusting screw 37 permits regulation of pressure of spring 35 upon the chain. For bulky materials the spring pressure is increased, while the converse is true for light materials.

It is thus seen that by utilizing the novel needle plate 16, a single foot lifting and chain swinging operation is all that is required to effect severing of the tail from the previously formed chain, and orienting the tail in position for backt acking for the commencement of a new line of stitching.

The above disclosure has been given by way of illustration and elucidation, and not by way of lirnitation, and it is desired to protect all embodiments of the herein disclosed inventive concept within the scope of the appended claims.

What is claimed is:

1. Means for backtacking the chain of stitches formed on a sewing machine in which thread looper-s interact in a stitch forming area to form a chain and movement of the thread can only be obtained by energizing the machine, said means comprising: a throat plate, cut out means in said throat plate forming a chain finger having a free end projecting from said throat plate, an area of stitch formation on said chain finger, said cut out means being spaced inwardly from the free end of said chain finger with a portion thereof out of the area of stitch formation within which portion thethreads forming the chain in the stitch forming area may be pulled so as to prevent chain formation during operation of the machine; feed means upon which the material to be sewn may be positioned for feeding to the area of stitch formation; and aligning means guiding the previously for/med free chain of stitches along the desired line of stitching of the material.

2. Means as in claim 1 in which said aligning means comprise: hold down means arranged to engage the free chain of stitches to be backtacked in line with the newly formed stitching, said hold down means spring biasing the interact in a stitch forming area to form a chain, and movement of the thread can only be obtained by energizing the machine, said method comprising the steps of: pulling a previously formed chain away from the stitch rforming area so that looper interaction and chain formation will be prevented during operation of the machine; positioning the material over the feed dogs of the machine so that the material will be fed to the area of stitch formation; aligning the previously for -med chain with the desired line of stitching of the material; and permitting the pulled chain to be moved by the fed material into the stitch forming area at the commencement of stitching of the material.

5. A method as in claim 4 in which the step of pulling the previously formed chain away from the stitch forming area is accomplished by forming an undercut in the needle plate adjacent the stitch forming area and moving the chain into the undercut.

6. A method as in claim 4 in which said aligning step is performed by: exerting a spring pressure on the previously formed chain to yieldingly maintain same along the desired line of stitches.

7. A method as in claim 4 in which the previously formed chain is cut off to form a predetermined length after it is pulled away from the stitch forming area.

8. A backt acking attachment for implementing the backtacking of a previously formed chain of stitches into a course of stitching being formed, said attachment comprising: a needle plate, having feed dog slots formed therein, cutout means in said needle plate forming a chain finger having a free end projecting from said needle plate, an area of stitch formation on said needle finger, said cutout means being spaced inwardly from the free end of said chain finger with a portion thereof out of the area of stitch formation to permit displacement of the thread from the stitch forming area whereby chain formation may be discontinued. i

9. An attachment as in claim 8 in which a chain clamping spring is formed on said needle plate serving to re tain the chain of stitches in a preselected position.

10. An attachment as in claim 8 in which a cutting knife is positioned at the front edge of the needle plate adjacent the line of stitching so as to permit cut off of the free chain at a predetermined length.

11. Means for backtack-ing the chain of stitches formed on a sewing machine in which the stitches are formed on finger means in a stitch forming area, and movement of the thread can only be obtained by energizing the machine, said means comprising: a throat plate, cutout means in said throat plate forming the finger means having a free end projecting from said throat plate, an area of stitch formation on said finger means, said cutout means being spaced inwardly from the free end of said finger means with a portion thereof out of the area of stitch formation; feed means upon which the maten'al to be sewn may be positioned for feeding to the area of stitch formation; hold down means remote from the finger means in the stitch forming area engaging the free end of a chain of stitches in line with the line of stitching of the material in which backt acking is to occur, said hold down means spring biasing the free chain into aligned position; and cut off means positioned adjacent said hold down means to form the free chain of stitches of a predetermined length.

12. A method for backtacking the chain of stitches formed on a sewing machine of the overlook type in which movement of the thread can only be obtained by energizing the machine, said method comprising the steps of: pulling a previously formed chain to pull the thread away from the stitch forming area; yieldingly engaging the previously formed chain which has been pulled away from the chain forming area; severing the end of the pulled away chm'n so that it is of a predetermined length; aligning the pulled away chain with the desired line of stitching of the material in which backtacking is to occur; and feeding the material into the machine so as to return the pulled chain of stitches to a position permitting chain formation as the material is sewn.

13. A baclrtacking attachment for implementing the backtacking of a previously formed chain of stitches into a course of stitching being formed on an overlook machine, said attaehment comprising: a needle plate having feed dog slots formed therein; cutout means in said needle plate forming a chain finger having a free end projecting from said needle plate, an area of stitch formation on said chain finger, said cutout means being spaced inwardly from the free end of said chain finger with a portion thereof out of the area of stitch formation; a clamping spring secured to the needle plate remote from chain form-ing area beneath which the previously formed chain of stitches may be yieldingly held; and a cutter blade adjacent said clamping spring to sever the previously formed chain at a predetermined length.

References Cited in the file of this patent UNITED STATES PATENTS 1,083,967 Weis et a1. Jan. 13, 1914 1,305,051 Berger May 27, 1919 1,324,736 Gardner Dec. 9, 1919 1,736,453 Maier Nov. 19, 1929 2,756,704 Lawber July 31, 1956 2,858,783 Lawber Nov. 4, 1958 

1. MEANS FOR BACKTACKING THE CHAIN OF STITCHES FORMED ON A SEWING MACHINE IN WHICH THREAD LOOPERS INTERACT IN A STITCH FORMING AREA TO FORM A CHAIN AND MOVEMENT OF THE THREAD CAN ONLY BE OBTAINED BY ENERGIZING THE MACHINE, SAID MEANS COMPRISING: A THROAT PLATE, CUT OUT MEANS IN SAID THROAT PLATE FORMING A CHAIN FINGER HAVING A FREE END PROJECTING FROM SAID THROAT PLATE, AN AREA OF STITCH FORMATION ON SAID CHAIN FINGER, SAID CUT OUT MEANS BEING SPACED INWARDLY FROM THE FREE END OF SAID CHAIN FINGER WITH A PORTION THEREOF OUT OF THE AREA OF STITCH FORMATION WITHIN WHICH PORTION THE THREADS FORMING THE CHAIN IN THE STITCH FORMING AREA MAY BE PULLED SO AS TO PREVENT CHAIN FORMATION DURING OPERATION OF THE MACHINE; FEED MEANS UPON WHICH THE MATERIAL TO BE SEWN MAY BE POSITIONED FOR FEEDING TO THE AREA OF STITCH FORMATION; AND ALIGNING MEANS GUIDING THE PREVIOUSLY FORMED FREE CHAIN OF STITCHES ALONG THE DESIRED LINE OF STITCHING OF THE MATERIAL.
 4. A METHOD FOR BACKTACKING THE CHAIN OF STITCHES FORMED ON A SEWING MACHINE IN WHICH THREAD LOOPERS INTERACT IN A STITCH FORMING AREA TO FORM A CHAIN, AND MOVEMENT OF THE THREAD CAN ONLY BE OBTAINED BY ENERGIZING THE MACHINE, SAID METHOD COMPRISING THE STEPS OF: PULLING A PREVIOUSLY FORMED CHAIN AWAY FROM THE STITCH FORMING AREA SO THAT LOOPER INTERACTION AND CHAIN FORMATION WILL BE PREVENTED DURING OPERATION OF THE MACHINE; POSITIONING THE MATERIAL OVER THE FEED DOGS OF THE MACHINE SO THAT THE MATERIAL WILL BE FED TO THE AREA OF STITCH FORMATION; ALIGNING THE PREVIOUSLY FORMED CHAIN WITH THE DESIRED LINE OF STITCHING OF THE MATERIAL; AND PERMITTING THE PULLED CHAIN TO BE MOVED BY THE FED MATERIAL INTO THE STITCH FORMING AREA AT THE COMMENCEMENT OF STITCHING OF THE MATERIAL. 